Intense light source



Nov. 20, 1962 J. F. MOTSON INTENSE LIGHT SOURCE Filed May 18, 1959 JAMES F. MOTSON AGENT United States Patent Ofiice 3,065,369 Patented Nov. 20, 1962 3,065,369 INTENSE LIGHT SOURCE James F. Motson, 798 Welsh Road, Huntingdon Valley, Pa. Filed May 18, 1959, Ser. No. 813,739 2 Claims. (Cl. 313-108) This invention relates to sources of light and in particular to light source packages using the combined prin ciples of electroluminescent light emission and photoluminescent light emission.

In light source devices where the primary source of light is an electroluminescent lamp the intensity of the light emission from such a lamp is dependent on the applied voltage and frequency of the stimulating electrical source, as well as the particular phosphors. If the voltage and frequency to be applied are fixed by factors outside the lamp itself, then in order to improve the light emission, techniques have been employed whereby the phosphors are arranged uniformly in the binder, and there is a resultant improvement in the output of light from the lamp.

For instance, if the lamp is employed to light a dial of an aeroplane instrument the voltage and frequency are fixed by the electrical power sources available in the aeroplane. It has been found however, that by uniformly placing the phosphors throughout the binding vehicle holding the phosphors, the light emission can be improved for the same applied voltage and frequency.

Irrespective of what improvements have been attained, by versions of this last technique, the search for more improvement in light emission in respect to electroluminescent devices continues. It would be highly desirable to provide a source of light which, although its phosphors are uniformly placed, and although there is a fixed voltage and frequency applied, could still produce an improved or increased light output.

It is therefore an object of this invention to provide an improved source of light.

It is a further object of this invention to provide a source of light having an output with a light intensity amplification.

In accordance with a main feature of the present invention there is provided a housing means holding phosphors which can be excited by light energy and provide light emission in response to said excitation. The housing means is formed so that the exciting light source is applied to a large surface area (providing thereby a large amount of exciting light), and the light output is transmitted from a relatively narrow surface area with this last area being located so that the cumulative effect of substantially all the light emission of the excited phosphors can be seen from this narrow surface area.

In accordance with another main feature of the present invention the housing means is arranged to have many of the above-described narrow surfaces placed or lying together so that there is provided a large area of intense light from the multiple cumulative effect.

In accordance with one preferred embodiment the large area is angularly shaped so that the light leaving any phosphor which has a path not perpendicular to the large area will be reflected back to the narrow surface thereby adding to the cumulative effect.

The foregoing and other objects and features of this invention will be best understood by reference to the following description of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 shows a top view sectional of a housing means of FIG. la with phosphors emitting light to produce a cumulative effect;

FIG. 1a shows a housing means having a large surface area and a narrow surface area;

FIG. 2 shows a schematic of the basic components of the light package;

FIG. 3 shows a schematic of the light source forming a jelly roll embodiment;

FIG. 4 is a schematic (sectional) of one embodiment to provide a maximum number of narrow surface areas at the light source end;

FIG. 5 shows the relationship between the amount of light applied to the area of emission for light source package of FIG. 6;

FIG. 6 is an embodiment of a light source package.

Referring to FIG. 1 and FIG. 1a there is a housing means 11 holding some phosphors 13 which have been excited by some exciting light, as indicated by arrows 12 (from a source not shown), and which are emitting light. The housing means 11 has at least one wide, or large, surface area 15 and at least one narrow surface area 17. In the preferred embodiment the housing means 11 has polished surfaces. If the phosphors 13 are excited by light applied to the surface area 15 there will be light emission from the surface area 19 lying opposite the surface area 15. Such an arrangement wherein the light has been obtained from the surface 19 has been the practice in the prior art light sources. The bundles of light rays from the three phosphors 13 are shown passing through an area of the surface 19 depicted by the loop 21. In other words, an observer looking at surface 19 would see a bundle of light rays from the three phosphors 13 which would fill the area enclosed by the loop 21. On the other hand, an observer facing the surface 17 would see a bundle of light rays from the phosphors 13 filling in a portion of the area of the surface 17 represented by the loop 23. It becomes clear that the looped area 23 receives light emission from phosphors directly and reflected from the polished surfaces along the depth of the surface 15 (or 19), so that there is a cumulative effect of the light emission seen from the surface 17. By making the surface 17 relatively narrow compared to the surface 15 (or 19), there is a substantial amplification of the light intensity as compared between the light seen at the surface 19 and the light seen at the surface 17. Another advantage in making the surface 17 relatively narrow lies in the fact there is very little attenuation of the exciting light through the surface 17 depth of the housing means 11. Although polished surfaces aid the light intensity at the narrow edge by steering the light rays reflected from the polished surfaces such as surface 19, it has been found that a housing means with unpolished surfaces also results in an intense light at the narrow surface area.

In FIG. 2 there is shown a housing means 29 containing phosphors. In a preferred embodiment the housing means 29 is an epoxy resin material into which there has been added photoluminescent phosphors. In FIG. 2 the layer 31 is a layer of electroluminescent material with electrical connectors 33 to be connected to a source of electrical power for excitation of the electroluminescent material. In a preferred embodiment the layer 31 comprises electroluminescent material with two suitable electrodes, one electrode being transparent and with the entire package mounted on and housed in a Mylar plastic wrapper. Such an exciting light means is described in more detail in my copending application entitled Fexible Lighting Source, filed May 18, 1959, Serial No. 813,740, now US. Patent No. 3,037,137 granted May 29, 1962. Such a flexible exciting light source permits the overall package to be easily formed into the embodiments depicted in FIGS. 3, 4 and 6. It is to be understood that although in a preferred embodiment the exciting light is applied to only one surface such as shown in FIG. 2, the lighting source (since it is flexible) can be wrapped around all the surfaces excepting the surface from which the light is to be observed, this surface being surface 35 in FIG. 2. In

other words, the lighting source can be wrapped around the surfaces as shown by the dashed line 37, in the event the resulting increased light intensity is commensurate with the efforts to effect the entire wrapping and this, of course, depends upon the utility of the device.

The embodiment of FIG. 3 is an example of an advantageously packaged light source of the present invention. The jelly rol 39 consists of a layer of photoluminescent material 41 wrapped as shown with an electroluminescent exciting light source 43. In accordance with the above discussion the light, per se, emanating from the narrow surface area of the photoluminescent material 41, will be intense, and with the narrow surface areas placed adjacent, as in FIG. 3, the entire end area of the jelly roll becomes an intense light source. In this embodiment the cumulative effect of the light from the photoluminescent phosphors is taken advantage of and the placing together of the narrow areas provides a multiple cumulative effect. In FIG. 3 the flexible electroluminescent lamp 43 is depicted for purposes of illustration with regard to its location, but is shown as being of greater width relative to the photoluminescent material than is actually true in practice. In actual practice the electroluminescent lamp end area is sufliciently narrow so that the jelly roll end surface is virtually made up of the photoluminescent material to provide a substantially uniform intense light source. The jelly roll light package of FIG. 3 lends itself to utility as a light source for instrument dials. As described in my co-pending application entitled Indicia Bearing Device, filed March 3, 1959, Serial No. 796,876, the photoluminescent material, or phosphors, can provide various coloring effects to the light source. As described in this last-mentioned application the colored light source has utility in aircraft dial devices, especially for night operations. The leads 45 in FIG. 3 are for connection to a source of electrical power to cause the electroluminescent material to glow thereby providing the exciting light.

In FIG. 4 there is shown another embodiment of the present invention. The narrow surfaces are again placed adjacent according to an S configuration or a sine wave configuration. The S lamp embodiment 47 includes a layer of photoluminescent material 49 formed together with a flexible electroluminescent lamp 51 having electrical power leads 53. The S lamp of FIG. 4 also takes advantage of the cumulative effect of the light from the phosphors at the narrow surface areas as well as the placing of the layers next to each other.

In FIG. there is shown a disc 55 which is a plastic, or glass, housing means holding photoluminescent phosphors therein. Under the disc 55 there is shown a flexible electroluminescent lamp 57 having two electrical leads 59. v The flexible lamp is placed adjacent the lower surface of the disc 55 according to the arrangement of FIG. 6. The lower edge of the disc 55 in a preferred embodiment is saw-toothed in shape but can have other configurations which will enable a maximum of light surface to be placed against the lower surface of disc 55. In the preferred embodiment shown in FIGS. 5 and 6, the amount of lighting surface is about 40% more than the top area 56 of the disc 55. The exciting light from the flexible electroluminescent lamp 57 excites the phosphors of the disc 55 and by the direct and reflected light from the polished surfaces of the disc 55 there is a cumulative effect of the light seen from the surface 56. In essence for a given area of primary lamp surface the intensity of the light is amplified as seen from the narrow surface area of the photoluminescent component of the light package.

In the embodiments of the present invention wherein the flexible light is applied to only selected surfaces (the narrow surface, or light emitting position being excepted), there can be applied to the other surfaces a reflecting coating such as a white or silver paint. The reflecting coating reflects the light which the polished surfaces fail to reflect and which ordinarily would pass from the large areas, such as the surface 19 of FIG. 1. The reflecting coating would be applied to, for instance, the surface 52 of FIG. 4, or surface 36 of FIG. 2.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

What I claim is:

l. A source of light comprising transparent housing means having first and second surface areas, said first surface being a polished surface said housing means holding a substantial quantity of light sensitive phosphors, said light sensitive phosphors being capable of producing light in response to an exciting light said first surface area being saw-tooth shaped and larger than said second area, said second area lying substantially parallel to the bases of the triangles formed by said saw-tooth shaped surface portions, and a source of exciting light disposed adjacent said first area to provide exciting light to said light sensitive phosphors thereby providing a cumulative effect of light emission from said light sensitive phosphors to said second surface to provide an intense light source at said second surface.

2. A source of light according to claim 1 wherein said phosphors are selected phosphors to provide a light emission in a predetermined frequency range thereby producing an intense colored light source.

Destriau: New Phenomenon of Electrophotoluminescence, Philosophical Magazine, vol. 38, 1947, pages 700 to 702, 711 to 713 and 723. 

1. A SOURCE OF LIGHT COMPRISING TRANSPARENT HOUSING MEANS HAVING FIRST AND SECOND SURFACE AREAS, SAID FIRST SURFACE BEING A POLISHED SURFACE SAID HOUSING MENS HOLDING A SUBSTANTIAL QUANTITY OF LIGHT SENSITIVE PHOSPHORS, SAID LIGHT SENSITIVE PHOSPHORS BEING CAPABLE OF PRODUCING LIGHT IN RESPONSE TO AN EXCITINVG LIGHT SURFACE AREA BEING SAW-TOOTH SHAPED ANDLARGER THAN SAID SECOND AREA, SAID SECOND AREA LYING SUBSTANTIALLY PARALLEL TO THE BASES 